 /*******************************************************************************
  * Copyright (c) 2005, 2006 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  * IBM Corporation - initial API and implementation
  *******************************************************************************/
 package org.eclipse.ui.internal.dialogs;

 import java.util.ArrayList ;
 import java.util.Collection ;
 import java.util.HashMap ;
 import java.util.Iterator ;
 import java.util.List ;
 import java.util.Map ;

 import org.eclipse.jface.preference.IPreferenceNode;
 import org.eclipse.jface.viewers.ITreeContentProvider;
 import org.eclipse.jface.viewers.TreeViewer;
 import org.eclipse.jface.viewers.Viewer;
 import org.eclipse.ui.dialogs.PatternFilter;
 import org.eclipse.ui.internal.preferences.WorkbenchPreferenceExtensionNode;

 /**
  * A class that handles filtering preference node items based on a supplied
  * matching string.
  *
  * @since 3.2
  *
  */
 public class PreferencePatternFilter extends PatternFilter {

     /**
      * this cache is needed because
      * WorkbenchPreferenceExtensionNode.getKeywordLabels() is expensive. When it
      * tracks keyword changes effectivly than this cache can be removed.
      */
     private Map keywordCache = new HashMap ();

     /**
      * Create a new instance of a PreferencePatternFilter
      *
      * @param isMatchItem
      */
     public PreferencePatternFilter() {
         super();
     }

     /*
      * Return true if the given Object matches with any possible keywords that
      * have been provided. Currently this is only applicable for preference and
      * property pages.
      */
     private String [] getKeywords(Object element) {
         List keywordList = new ArrayList ();
         if (element instanceof WorkbenchPreferenceExtensionNode) {
             WorkbenchPreferenceExtensionNode workbenchNode = (WorkbenchPreferenceExtensionNode) element;

             Collection keywordCollection = (Collection ) keywordCache
                     .get(element);
             if (keywordCollection == null) {
                 keywordCollection = workbenchNode.getKeywordLabels();
                 keywordCache.put(element, keywordCollection);
             }
             if (!keywordCollection.isEmpty()){
                 Iterator keywords = keywordCollection.iterator();
                 while (keywords.hasNext()) {
                     keywordList.add(keywords.next());
                 }
             }
         }
         return (String []) keywordList.toArray(new String [keywordList.size()]);
     }

     /*
      * (non-Javadoc)
      *
      * @see org.eclipse.ui.internal.dialogs.PatternFilter#isElementSelectable(java.lang.Object)
      */
     public boolean isElementSelectable(Object element) {
         return element instanceof WorkbenchPreferenceExtensionNode;
     }

     /* (non-Javadoc)
      * @see org.eclipse.ui.dialogs.PatternFilter#isElementVisible(org.eclipse.jface.viewers.Viewer, java.lang.Object)
      */
     public boolean isElementVisible(Viewer viewer, Object element) {
         // Preference nodes are not differentiated based on category since
 // categories are selectable nodes.
 if (isLeafMatch(viewer, element)) {
             return true;
         }

         ITreeContentProvider contentProvider = (ITreeContentProvider) ((TreeViewer) viewer)
                 .getContentProvider();
         IPreferenceNode node = (IPreferenceNode) element;
         Object [] children = contentProvider.getChildren(node);
         // Will return true if any subnode of the element matches the search
 if (filter(viewer, element, children).length > 0) {
             return true;
         }
         return false;
     }

     /* (non-Javadoc)
      * @see org.eclipse.ui.dialogs.PatternFilter#isLeafMatch(org.eclipse.jface.viewers.Viewer, java.lang.Object)
      *
      */
     protected boolean isLeafMatch(Viewer viewer, Object element) {
         IPreferenceNode node = (IPreferenceNode) element;
         String text = node.getLabelText();

         if (wordMatches(text)) {
             return true;
         }

         // Also need to check the keywords
 String [] keywords = getKeywords(node);
         for (int i = 0; i < keywords.length; i++){
             if (wordMatches(keywords[i])) {
                 return true;
             }
         }
         return false;
     }

 }

